Method for forming thin film

ABSTRACT

The present invention relates to a method for forming a thin film, and more particularly, to a method for forming a thin film comprising steps of:i) absorbing a growth inhibitor for forming a thin film on a surface of a substrate, the growth inhibitor for forming a thin film being represented by Chemical Formula 1 below; and ii) adsorbing a Ti-based thin film precursor on a surface of a substrate on which the growth inhibitor is adsorbed.AnBmXo  [Chemical Formula 1]wherein A is carbon or silicon, B is hydrogen or a C1-C3 alkyl, X is a halogen, n is an integer of 1 to 15, o is an integer of 1 or more, and m is 0 to 2n+1.According to the present invention, it is possible to suppress side reactions to appropriately lower a thin film growth rate and remove process byproducts in the thin film, thereby preventing corrosion or deterioration and greatly improving step coverage and thickness uniformity of a thin film, even when the thin film is formed on a substrate having a complex structure.

CROSS-REFERENCE TO RELATED APPLICATIONS

The application claims priority under 35 U.S.C. § 119 to Korean PatentApplication No. 10-2019-0118416, filed on Sep. 25, 2019, in the KoreanIntellectual Property Office, the disclosure of which is incorporatedherein by reference in its entirety.

TECHNICAL FIELD

The following disclosure relates to a method for forming a thin film,and more particularly, to method for forming a thin film capable ofsuppressing side reactions to appropriately lower the thin film growthrate and remove process byproducts in the thin film, thereby preventingcorrosion or deterioration and greatly improving the step coverage andthickness uniformity of a thin film even when the thin film is formed ona substrate having a complex structure.

BACKGROUND

The degree of integration of memory and non-memory semiconductor devicesis increasing day by day. As the structure thereof becomes more and morecomplex, the importance of step coverage in the deposition of variousthin films on a substrate is increasing.

A thin film for a semiconductor is made of a metal nitride, metal oxide,metal silicide, or the like. Metal nitride thin films include titaniumnitride (TiN), tantalum nitride (TaN), zirconium nitride (ZrN), and thelike. The thin films are generally used as a diffusion barrier betweenthe silicon layer of a doped semiconductor and an interlayer wiringmaterial such as aluminum (Al), copper (Cu), or the like. However, whena tungsten (W) thin film is deposited on the substrate, the tungsten (W)thin film is used as an adhesion layer.

In order to obtain a thin film having excellent and uniform physicalproperties when deposited on the substrate, it is essential that theformed thin film have a high step coverage. Therefore, an atomic layerdeposition (ALD) process employing a surface reaction, rather than achemical vapor deposition (CVD) process mainly employing a gas phasereaction, is utilized; however, there are still problems for realizationof 100% step coverage.

In addition, in the case of using titanium tetrachloride (TiCl₄) todeposit titanium nitride (TiN), a representative material among themetal nitrides, process by-products such as chlorides remain in theprepared thin film, causing corrosion of metals such as aluminum, andthe like, and the production of non-volatile byproducts leads todeterioration of film quality.

Therefore, it is necessary to develop a method for forming a thin filmwhich is capable of forming a thin film having a complex structure andwhich does not lead to corrosion of an interlayer wiring material.

Documents of the Related Art

(Patent Document 1) Korean Patent Laid-Open Publication No. 2006-0037241

SUMMARY

An embodiment of the present disclosure is directed to providing amethod for forming a thin film capable of suppressing side reactions toappropriately lower the growth rate of the thin film and remove processbyproducts therein, thereby preventing corrosion or deterioration andgreatly improving the step coverage and thickness uniformity of the thinfilm, even when the thin film is formed on a substrate having a complexstructure.

All of the above objects and other objects of the present disclosure canbe achieved by the present disclosure described below.

To achieve the above-mentioned objects, the present disclosure presentsa method for forming a thin film comprising steps of:

i) adsorbing a growth inhibitor for forming a thin film on a surface ofa substrate, the growth inhibitor for forming a thin film beingrepresented by Chemical Formula 1 below; and ii) adsorbing a Ti-basedthin film precursor on a surface of a substrate on which the growthinhibitor is adsorbed.

AnBmXo  [Chemical Formula 1]

wherein A is carbon or silicon, B is hydrogen or a C1-C3 alkyl, X is ahalogen, n is an integer of 1 to 15, o is an integer of 1 or more, and mis 0 to 2n +1.

In addition, the present invention relates to an apparatus for preparinga thin film, comprising an atomic layer deposition (ALD) chamber, afirst vaporizer for vaporizing the growth inhibitor for forming a thinfilm, a first transfer unit for transferring the vaporized growthinhibitor into the ALD chamber, a second vaporizer for vaporizing aTi-based thin film precursor, and a second transfer unit fortransferring the vaporized Ti-based thin film precursor into the ALDchamber.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a process chart illustrating a conventional atomic layerdeposition (ALD) process.

FIG. 2 is a flowchart illustrating an ALD process according to anembodiment of the present disclosure.

FIG. 3 is a graph illustrating the change in thin film thicknessaccording to the increase in ALD cycle for Example 7 (SP-TiCl₄) andComparative Example 1 (TiCl₄) of the present disclosure.

FIG. 4 is a graph illustrating the change in deposition rate accordingto feeding time of growth inhibitor (SP) for forming a thin film per ALDcycle for Examples 7-1 to 7-3 and Comparative Example 1 of the presentdisclosure.

FIG. 5 illustrates transmission electron microscope (TEM) images of TiNthin films deposited for Example 1 (SP-TiCl₄) and Comparative Example 1(TiCl₄) of the present disclosure.

DETAILED DESCRIPTION OF EMBODIMENTS

Hereinafter, a method for forming a thin film is described in detail.

The present inventors found that when a halogen-substituted compoundhaving a predetermined structure is first adsorbed as a growth inhibitorbefore the adsorption of a Ti-based thin film precursor on a surface ofa substrate loaded inside an atomic layer deposition (ALD) chamber, thegrowth rate of the thin film to be formed after deposition is loweredand a significant reduction of the halides remaining as processbyproducts is achieved, thereby greatly improving step coverage, and thelike. Based on this finding, the present inventors made a significanteffort on further research and thereby completed the present disclosure.

The method for forming a thin film of the present disclosure ischaracterized by comprising steps of i) adsorbing a growth inhibitor forforming a thin film on a surface of a substrate, the growth inhibitorfor forming a thin film being represented by Chemical Formula 1 below;and ii) adsorbing a Ti-based thin film precursor on a surface of asubstrate on which the growth inhibitor is adsorbed.

AnBmXo  [Chemical Formula 1]

wherein A is carbon or silicon, B is hydrogen or a C1-C3 alkyl, X is ahalogen, n is an integer from 1 to 15, o is an integer of 1 or more, andm is from 0 to 2n+1. In this case, side reactions occurring duringformation of the thin film may be suppressed to lower the thin filmgrowth rate while also achieving removal of process byproducts in thethin film, and thus corrosion or deterioration may be reduced and stepcoverage and thickness uniformity of a thin film may be greatly improvedeven when the thin film is formed on a substrate having a complexstructure.

In the step of i) adsorbing the growth inhibitor for forming a thin filmon the surface of the substrate, the feeding time for the growthinhibitor is preferably 1 to 10 seconds, more preferably 1 to 5 seconds,even more preferably 2 to 5 seconds, and still more preferably 2 to 4seconds. Within this range, there are advantages in that the thin filmgrowth rate is low, and the step coverage and economic feasibility areexcellent.

The feeding time of the growth inhibitor for forming a thin film in thepresent disclosure is based on a chamber having a volume of 15 to 20L ata flow rate of 0.5 to 5 mg/s, and more specifically, a chamber having avolume of 18L at a flow rate of 1 to 2 mg/s.

The step of i) adsorbing the growth inhibitor for forming a thin film onthe surface of the substrate may preferably comprise a step of injectingthe growth inhibitor for forming a thin film into an atomic layerdeposition (ALD) chamber and adsorbing the growth inhibitor onto asurface of a loaded substrate, and thereby suppressing side reactions,lowering the deposition rate to lower the growth rate of the thin film,and removing process byproducts in the thin film.

The step of i) adsorbing the growth inhibitor for forming a thin film onthe surface of the substrate may preferably comprise a step of purgingthe remaining inhibitor unadsorbed on a surface of the substrate forforming the thin film with a purge gas, and thereby suppressing sidereactions to lower the growth rate of the thin film and to removeprocess byproducts in the thin film, thereby greatly improving the stepcoverage and thickness uniformity of the thin film even when the thinfilm is formed on a substrate having a complex structure.

In addition, the step of ii) adsorbing a Ti-based thin film precursormay preferable comprise a step of purging the remaining unadsorbedTi-based thin film precursor with a purge gas.

The method for forming a thin film may preferably comprise steps ofsupplying a reaction gas after adsorption of a Ti-based thin filmprecursor on the surface of the substrate, and purging reactionbyproducts of the Ti-based thin film precursor and the reaction gas witha purge gas.

In one preferred embodiment, the method for forming a thin film maycomprise steps of: a) vaporizing the growth inhibitor for forming a thinfilm and adsorbing the growth inhibitor on a surface of a substrateloaded in an atomic layer deposition (ALD) chamber; b) primary purgingof the inside of the ALD chamber with a purge gas; c) vaporizing aTi-based thin film precursor and adsorbing the thin film precursorcompound on the surface of the substrate loaded in the ALD chamber; d)secondary purging of the inside of the ALD chamber with a purge gas; e)supplying a reaction gas into the ALD chamber; and f) tertiary purgingof the inside of the ALD chamber with a purge gas. In this case, thereare advantages in that the thin film growth rate is appropriatelylowered, the process byproducts which may be generated are effectivelyremoved even if the deposition temperature is increased at the time offormation of the thin film, and thus the specific resistance of the thinfilm is reduced and the step coverage is greatly improved.

The growth inhibitor for forming a thin film and the Ti-based thin filmprecursor may preferably be transferred into the ALD chamber, namely tothe surface of the substrate, by a vapor flow control (VFC) method, adelivery liquid injection (DLI) method or a liquid delivery system (LDS)method, and may more preferably be transferred into the ALD chamber bythe LDS method.

The ratio of the feeding amount (mg/cycle) between the growth inhibitorfor forming a thin film and the Ti-based precursor in the ALD chambermay preferably be from 1:1.5 to 1:20, more preferably from 1:2 to 1:15,even more preferably from 1:2 to 1:12, and still more preferably from1:2.5 to 1:10. Within this range, a high reduction rate of the thin filmgrowth rate (GPC) per cycle and a great reduction of the processbyproducts may be achieved.

The Ti-based thin film precursor to be employed is not particularlylimited as long as it is a Ti-based thin film precursor generally usedin the ALD method.

In one preferred embodiment, the thin film precursor may be titaniumtetrahalide.

The titanium tetrahalide may preferably be at least one selected fromthe group consisting of TiF₄, TiCl₄, TiBr₄, and TiI₄, and for example,from an economic standpoint, may preferably be TiCl₄, but the titaniumtetrahalide is not limited thereto.

However, since the titanium tetrahalide does not decompose at roomtemperature but exists in a liquid state due to having excellent thermalstability, the titanium tetrahalide may be usefully employed for thedeposition of a thin film as the thin film precursor of ALD.

As an example, the Ti-based thin film precursor may be mixed with anon-polar solvent and injected into the chamber. In this case, there isan advantage in that the viscosity or vapor pressure of the Ti-basedthin film precursor may be easily adjusted.

The non-polar solvent may preferably be one or more selected from thegroup consisting of alkanes and cycloalkanes. In this case, there is anadvantage in that even when including an organic solvent having lowreactivity and solubility with easy moisture management capability, thestep coverage is improved even if the deposition temperature isincreased during formation of the thin film.

In a more preferred embodiment, the non-polar solvent may comprise a C1to C10 alkane or a C3 to C10 cycloalkane, and preferably a C3 to C10cycloalkane. In this case, there are advantages in that the reactivityand solubility are low and moisture management may be easily achieved.

In the present disclosure, the notations C1, C3, and the like, representthe number of carbons.

The cycloalkane may preferably be a C3 to C10 monocycloalkane. Among themonocycloalkanes, cyclopentane is liquid at room temperature and has thehighest vapor pressure, which is preferable in the vapor depositionprocess, but the solvent is not limited thereto.

The non-polar solvent has, for example, a solubility in water (25° C.)of 200 mg/L or less, preferably 50 to 200 mg/L, and more preferably 135to 175 mg/L. Within this range, there are advantages in that thereactivity for the Ti-based thin film precursor is low and moisturemanagement may be easily performed.

In the present disclosure, the method employed for the measurement ofsolubility is not particularly limited as long as the method orstandards thereof correspond to those generally used in the art to whichthe present disclosure pertains, and for example, a saturated solutionmay be measured by a high performance liquid chromatography (HPLC)method.

The non-polar solvent may preferably be included at a ratio of 5 to 95wt %, more preferably 10 to 90 wt %, even more preferably 40 to 90 wt %,and most preferably 70 to 90 wt %, based on the total weight of theTi-based thin film precursor and the non-polar solvent.

Injection of the non-polar solvent at a content exceeding the upperlimit described above may cause impurities, thereby increasing theresistance and number of impurities in the thin film, while injection ata content below the lower limit may cause the effect of improvement ofthe step coverage and reduction of impurities such as chlorine (Cl)ions, to be obtained through addition of the solvent, to be small.

In the method for forming a thin film, for example, the reduction rateof a thin film growth rate (Å/cycle) per cycle calculated by Equation 1below may be −5% or less, preferably −10% or less, more preferably −20%or less, even more preferably −30% or less, still more preferably −40%or less, and most preferably −45% or less. Within this range, excellentstep coverage and film thickness uniformity may be achieved.

Reduction rate of thin film growth rate per cycle (%)=[(thin film growthrate per cycle when growth inhibitor for forming thin film is used—thinfilm growth rate per cycle when growth inhibitor for forming thin filmis not used)/thin film growth rate per cycle when growth inhibitor forforming thin film is not used]×100  [Equation 1]

In the method for forming a thin film, the residual halogen intensity(c/s) of the thin film formed after 200 cycles, which is measured basedon SIMS, may preferably be 10,000 or less, more preferably 8,000 orless, even more preferably 7,000 or less, and still more preferably6,000 or less. Within this range, excellent prevention of corrosion anddeterioration may be achieved.

In the present disclosure, the purging is preferably performed at 1,000to 10,000 sccm, more preferably at 2,000 to 7,000 sccm, and still morepreferably at 2,500 to 6,000 sccm. Within this range, the thin filmgrowth rate per cycle may be reduced to a desirable range and theprocess byproducts may be reduced.

The atomic layer deposition (ALD) process is very beneficial topreparation of an integrated circuit (IC) that requires a high aspectratio, and particularly has advantages such as excellent stepconformality and uniformity, precise thickness control, and the like,due to the self-limiting thin film growth mechanism.

The method for forming a thin film may be performed, for example, at adeposition temperature in the range of 50 to 900° C., preferably at adeposition temperature in the range of 300 to 700° C., more preferablyat a deposition temperature in the range of 350 to 600° C., even morepreferably at a deposition temperature in the range of 400 to 550° C.,and still more preferably at a deposition temperature in the range of400 to 500° C. Within this range, it is possible to achieve growth of athin film with excellent film quality while realizing the ALD processcharacteristics.

The method for forming a thin film may be performed, for example, at adeposition pressure in the range of 0.1 to 10 Torr, preferably at adeposition pressure in the range of 0.5 to 5 Torr, and most preferablyat a deposition pressure in the range of 1 to 3 Torr. Within this range,it is possible to obtain a thin film having uniform thickness.

In the present disclosure, the deposition temperature and depositionpressure may be measured as the temperature and pressure to be formed inthe deposition chamber, or may be measured as the temperature andpressure to be applied to the substrate in the deposition chamber.

The method for forming a thin film may preferably comprise steps ofraising the temperature in the chamber to a deposition temperaturebefore the injection of the growth inhibitor for forming a thin filminto the chamber; and/or injection and purging of an inert gas into thechamber before the injection of the growth inhibitor for forming a thinfilm.

In addition, the present disclosure may comprise an apparatus forpreparing a thin film capable of implementing the method for forming athin film described in the present disclosure, the apparatus forpreparing a thin film comprising an atomic layer deposition (ALD)chamber, a first vaporizer for vaporizing the growth inhibitor forforming a thin film, a first transfer unit for transferring thevaporized growth inhibitor into the ALD chamber, a second vaporizer forvaporizing a Ti-based thin film precursor, and a second transfer unitfor transferring the vaporized Ti-based thin film precursor into the ALDchamber. Here, the vaporizer and the transfer unit to be employed arenot particularly limited, as long as they are generally used in the artto which the present disclosure pertains.

As a specific example, the method for forming a thin film is describedas follows.

First, the substrate on which the thin film is to be formed is placed ina deposition chamber capable of atomic layer deposition.

The substrate may comprise a semiconductor substrate such as a siliconsubstrate, silicon oxide, or the like.

The substrate may further comprise a conductive layer or an insulatinglayer formed thereon.

In order to deposit the thin film on the substrate placed in thedeposition chamber, the above-described growth inhibitor for forming athin film and the Ti-based thin film precursor or a mixture of the thinfilm precursor compound and the non-polar solvent are prepared,respectively.

Then, the prepared inhibitor for forming a thin film is injected intothe vaporizer and converted into a vapor phase, transferred to thedeposition chamber, and then adsorbed on the substrate, after which theremaining unadsorbed inhibitor is purged.

Next, the prepared thin film precursor compound or a mixture of theTi-based thin film precursor and the non-polar solvent is injected intothe vaporizer and converted into a vapor phase, transferred to thedeposition chamber, and then adsorbed on the substrate, after which theunadsorbed composition for forming a thin film is purged.

In the present disclosure, as the method employed for transferring theinhibitor for forming a thin film, the thin film precursor compound, andthe like, to the deposition chamber, for example, a vapor flow control(VFC) method for transferring a volatilized gas through utilization of amass flow controller (MFC), or a liquid delivery system (LDS) method fortransferring a liquid through utilization of a liquid mass flowcontroller (LMFC), and preferably, the LDS method, may be employed.

Here, as a transfer gas or diluent gas for moving the inhibitor forforming a thin film, the Ti-based thin film precursor, and the like,onto the substrate, one or a mixture of two or more gases selected fromargon (Ar), nitrogen (N₂), and helium (He) may be used, but the gas isnot limited thereto.

In the present disclosure, the purge gas may be, for example, an inertgas, and preferably, the transfer gas or dilution gas above.

Next, the reaction gas is supplied. The reaction gas is not particularlylimited as long as it is a reaction gas generally used in the art towhich the present disclosure pertains, and may preferably comprise areducing agent, a nitriding agent, or an oxidizing agent. A metal thinfilm is formed through reaction of the reducing agent with the Ti-basedthin film precursor adsorbed on the substrate, while a metal nitridethin film is formed through reaction of the nitriding agent and a metaloxide thin film is formed through reaction of the oxidizing agent.

Preferably, the reducing agent may be ammonia gas (NH₃) or hydrogen gas(H₂), the nitriding agent may be nitrogen gas (N₂), and the oxidizingagent may be one or more selected from the group consisting of H₂O,H₂O₂, O₂, O₃, and N₂O.

Next, the unreacted residual reaction gas is purged by using the inertgas. Thus, not only the excess reaction gas but also any generatedbyproducts may be removed together.

As described above, a unit cycle may comprise steps of adsorbing theinhibitor for forming a thin film on the substrate, purging theunadsorbed inhibitor for forming a thin film, adsorbing the Ti-basedthin film precursor on the substrate, purging the unadsorbed compositionfor forming a thin film, supplying a reaction gas, and purging theresidual reaction gas, and the unit cycle may be repeated to form a thinfilm having a desired thickness.

The unit cycle may be performed, for example, from 100 to 1000 times,preferably 100 to 500 times, and more preferably 150 to 300 times.Within this range, the desired thin film s characteristics may be wellexpressed.

FIG. 1 is a process chart illustrating the conventional ALD process, andFIG. 2 is a flowchart illustrating the ALD process according to anembodiment of the present disclosure. Referring to FIG. 1, as in theconventional ALD process, when protection of the surface of thesubstrate is not achieved by first adsorbing the growth inhibitor forforming a thin film according to the present disclosure beforeadsorption of the Ti-based thin film precursor (TiCl₄), processby-products such as HCl remain in the thin film (TiN) due to reactionwith the reaction gas (NH₃), and thus the performance of the substrateis lowered due to corrosion or deterioration. However, as shown in FIG.2, when the surface of the substrate is protected (achieving surfaceprotection; SP) by first adsorbing the growth inhibitor (TSI) forforming a thin film according to the present disclosure beforeadsorption of the Ti-based thin film precursor (TiCl₄), the processby-products such as HCl generated through reaction with the reaction gas(NH₃) at the time of formation of the thin film (TiN) are removedtogether with the growth inhibitor for forming a thin film, therebypreventing corrosion or deterioration of the substrate, and further,appropriately lowering the thin film growth rate per cycle to improvethe step coverage and film thickness uniformity.

The growth inhibitor for forming a thin film of the present disclosureis characterized by a compound represented s by Chemical Formula 1below.

AnBmXo  [Chemical Formula 1]

wherein A is carbon or silicon, B is hydrogen or a C1-C3 alkyl, X is ahalogen, n is an integer from 1 to 15, o is an integer of 1 or more, andm is from 0 to 2n+1. In this case, side reactions occurring duringformation of the thin film may be suppressed to lower the thin filmgrowth rate while also achieving removal of process byproducts in thethin film, and thus corrosion or deterioration may be reduced and stepcoverage and thickness uniformity of a thin film may be greatly improvedeven when the thin film is formed on a substrate having a complexstructure.

In Chemical Formula 1, B is preferably hydrogen or methyl, n ispreferably an integer from 2 to 15, more preferably an integer from 2 to10, even more preferably an integer from 2 to 6, and still morepreferably an integer from 4 to 6. Within this range, an effect ofremoving the process byproducts may be large and excellent step coveragemay be achieved.

In Chemical Formula 1, X may be one or more selected from the groupconsisting of, for example, F, Cl, Br and I, and is preferably Cl(chlorine), in which case side reactions may be suppressed and processby-products may be effectively removed.

In Chemical Formula 1, o may preferably be an integer from 1 to 5, morepreferably an integer from 1 to 3, and even more preferably may be 1 or2. Within this range, an effect of reducing the deposition rate may belarge, which is more effective for improving the step coverage.

M is preferably from 1 to 2n+1, and more preferably from 3 to 2n+1.Within this range, the effect of removing the process byproducts may belarge and excellent step coverage may be achieved.

The compound represented by Chemical Formula 1 may preferably be abranched, cyclic or aromatic compound, and may be specifically one ormore selected from the group consisting of 1,1-dichloroethane,1,2-dichloroethane, dichloromethane, 2-chloropropane, 1-chloropropane,1,2-dichloropropane, 1,3-dichloropropane, 2,2-dichloropropane,1-chloropentane, 2-chloropentane, 3-chloropentane, chlorocyclopentane,n-butylchloride, tert-butyl chloride, sec-butyl chloride, isobutylchloride, 1,2-dichlorobenzene, 1,4-dichlorobenzene,trimethylchlorosilane, trichloropropane, 2-chloro-2-methylbutane,2-methyl-1-pentane, and the like. In this case, there are advantages inthat the effect of removing the process byproducts is large andexcellent step coverage is achieved.

The compound represented by Chemical Formula 1 is preferably used in anatomic layer deposition (ALD) process, and in this case, there areadvantages in that the compound acts as a growth inhibitor toeffectively protect the surface of the substrate and effectively removeprocess byproducts without interfering with adsorption of the Ti-basedthin film precursor.

The compound represented by Chemical Formula 1 is preferably a liquid atroom temperature (22° C.), may have a density of 0.8 to 1.5 g/cm³, avapor pressure (20° C.) of 1 to 300 mmHg, and solubility in water (25°C.) of 200 mg/L or less. Within this range, excellent step coverage andthickness uniformity may be achieved.

More preferably, the compound represented by Chemical Formula 1 may havea density of 0.85 to 1.3 g/cm³, a vapor pressure (20° C.) of 1 to 260mmHg, and solubility in water (25° C.) of 160 mg/L or less. Within thisrange, excellent step coverage and thickness uniformity of the thin filmmay be achieved.

The semiconductor substrate of the present disclosure is characterizedby being prepared by the method for forming a thin film of the presentdisclosure, and in this case, it is possible to appropriately lower thethin film growth rate and also remove process byproducts in the thinfilm by suppressing side reactions, thereby preventing corrosion ordeterioration and greatly improving the step coverage and thicknessuniformity of the thin film.

The prepared thin film preferably has a thickness of 20 nm or less, aspecific resistance value of 0.1 to 400 μΩ⋅cm, a halogen content of10,000 ppm or less, and a step coverage of 90% or more. Within thisrange, the prepared thin film may have excellent performance as adiffusion barrier film, and the corrosion of a metal wiring material maybe reduced, but the present disclosure not limited thereto.

The thin film may have, for example, a thickness of 5 to 20 nm,preferably 10 to 20 nm, even more preferably 15 to 18.5 nm, and stillmore preferably 17 to 18.5 nm. Within this range, the thin film may haveexcellent characteristics.

The thin film may have a specific resistance value of, for example, 0.1to 400 μΩ⋅cm, preferably 50 to 400 μΩ⋅cm, more preferably 200 to 400μΩ⋅cm, even more preferably 300 to 400 μΩ⋅cm, still more preferably 330to 380 μΩ⋅cm, and most preferably 340 to 370 μΩ⋅cm. Within this range,the thin film may have excellent characteristics.

The thin film may have a halogen content of more preferably 9,000 ppm orless, or 1 to 9,000 ppm; even more preferably 8,500 ppm or less, or 100to 8,500 ppm; and still more preferably 8,200 ppm or less, or 1,000 to8,200 ppm. Within this range, the thin film may have excellentcharacteristics and the corrosion of the metal wiring material may bereduced.

The thin film may have, for example, step coverage of 80% or more,preferably 90% or more, and more preferably 92% or more. Within thisrange, even if a thin film has a complex structure, the thin film iscapable of being easily deposited on the substrate, thereby enablingapplication to a next generation semiconductor device.

The prepared thin film may be, for example, a TiN thin film or a TiO₂thin film.

Hereinafter, preferable Examples of the present disclosure will bedescribed in order to facilitate understanding of the presentdisclosure. However, it will be apparent to those skilled in the artthat the following Examples are provided only to illustrate the presentdisclosure, various changes and modifications can be made within thespirit and the scope of the disclosure, and these variations andmodifications are included within the scope of the appended claims.

EXAMPLES Examples 1 to 7

A growth inhibitor for forming a thin film, shown in Table 1 below, andTiCl₄, as a Ti-based thin film precursor, were prepared, respectively.The prepared growth inhibitor for forming a thin film was placed in acanister and supplied to a vaporizer heated at 150° C. at a flow rate of0.05 g/min using a liquid mass flow controller (LMFC) at roomtemperature. The vaporized growth inhibitor for forming a thin film,converted into the vapor phase in the vaporizer, was injected into adeposition chamber loaded with a substrate for 3 seconds, after whichargon purging was performed by supplying argon gas at 3000 sccm for 6seconds. Here, the pressure in the reaction chamber was controlled to be1.3 Torr. Next, the prepared TiCl₄ was placed in a separate canister andsupplied to a separate vaporizer heated at 150° C. at a flow rate of0.05 g/min using an LMFC at room temperature. The vaporized TiCl₄′converted to the vapor phase in the vaporizer, was injected into thedeposition chamber for 3 seconds, after which argon purging wasperformed by supplying argon gas at 3000 sccm for 6 seconds. Here, thepressure in the reaction chamber was controlled to be 1.3 Torr. Next,ammonia as a reaction gas was injected into the reaction chamber for 5seconds, and then argon purging was performed for 10 seconds. Here, thesubstrate on which a metal thin film was to be formed was heated to 460°C. This process was repeated 200 times to form a TiN thin film as aself-limiting atomic layer.

TABLE 1 Growth inhibitor for forming a thin film Example 12-chloro-2-methylbutane Example 2 n-butyl chloride Example 3trimethylchlorosilane Example 4 2-chloropropane Example 51,2,3-trichloropropane Example 6 2-methyl-1-pentane Example 71,2-dichlorobenzene

Comparative Example 1

A TiN thin film was formed on a substrate in the same manner as inExample 1, except that the growth inhibitor for forming a thin film wasnot employed and thus the step of purging the unadsorbed growthinhibitor for forming a thin film was omitted.

Comparative Examples 2 and 3

A TiN thin film was formed on a substrate in the same manner as inExample 1, except that pentane or cyclopentane was used instead of thegrowth inhibitor for forming a thin film described in Table 1 above.

Experimental Example

1) Deposition Evaluation

Referring to Table 2 below, Example 1, in which chloro-2-methylbutanewas used as the growth inhibitor for forming a thin film, was comparedwith Comparative Example 1, in which the growth inhibitor for forming athin film was not included. As a result, the deposition rate of Example1 was 0.20 Å/cycle, which represents over a 55.5% reduction whencompared with the deposition rate of Comparative Example 1. It could beconfirmed that Examples 2 to 7 also had deposition rates similar to thatof Example 1. Further, it could be confirmed that Comparative Examples 2and 3, using pentane or cyclopentane instead of the growth inhibitor forforming a thin film according to the present disclosure, also had adeposition rate equal to that of Comparative Example 1. Here, thereduction in deposition rate means that the CVD depositioncharacteristics are changed to ALD deposition characteristics, and thusmay be used as an index for improvement of the step coveragecharacteristics.

TABLE 2 Deposition Rate Growth Inhibitor (Å/cycle) Example 12-chloro-2-methylbutane 0.20 Example 2 n-butyl chloride 0.31 Example 3trimethylchlorosilane 0.28 Example 4 2-chloropropane 0.20 Example 51,2,3-trichloropropane 0.32 Example 6 2-methyl-1-pentane 0.28 Example 71,2-dichlorobenzene 0.30 Comparative X 0.45 Example 1 ComparativePentane 0.45 Example 2 Comparative Cyclopentane 0.45 Example 3

In addition, as shown in Table 3, it could be confirmed that thedeposition rate was continuously reduced according to the feeding amountof chloro-2-methylbutane, the growth inhibitor for forming a thin film.Here, Example 1-1 was performed in the same manner as in Example 1,except for the feeding amount of the growth inhibitor for forming a thinfilm per cycle.

TABLE 3 Comparative Example 1 Example 1 Example 1-1 Feeding amount per 01.6 3.2 ALD cycle (mg/cycle) Deposition rate 0.45 0.20 0.02 (Å/cycle)

2) Impurity Reduction Characteristics

SIMS analysis was performed to compare the impurity reductioncharacteristics, that is, the process byproduct reductioncharacteristics, of the TiN thin films deposited in Example 1 andComparative Example 1, the results of which are shown in Table 4 below.

TABLE 4 Example Comparative 1 Example 1 Feeding amount per ALD 1.6 0cycle (mg/cycle) Cl intensity (c/s) 5907.05 17270.25

As shown in Table 4, it could be confirmed that the impurities ofExample 1, in which the growth inhibitor for forming a thin filmaccording to the present disclosure was employed, were reduced to about⅓ in comparison to Comparative Example 1, in which the growth inhibitorwas not employed.

Further, FIG. 3 is a graph showing the change in thickness of the thinfilm according to the increase in atomic layer deposition (ALD) cycle ofExample 7 (SP-TiCl₄) and Comparative Example 1 (TiCl₄) of the presentdisclosure, wherein it could be confirmed that the thickness of the thinfilm in Example 7 became significantly thinner.

In addition, FIG. 4 is a graph illustrating the change in depositionrate according to the feeding time of a growth inhibitor (SP) forforming a thin film per ALD cycle of Examples 7-1 to 7-3 and ComparativeExample 1 of the present disclosure, wherein it could be confirmed thatwhen the inhibitor for forming a thin film according to the presentdisclosure was not used, as in Comparative Example 1, the depositionrate was 0.45 Å/cycle, whereas in Examples 7-1, 7-2, and 7-3, in whichthe growth inhibitor for forming a thin film according to the presentdisclosure was injected in an amount of 0.7 sec, 1 sec, and 2 sec,respectively, the deposition rate was significantly thinned to 0.35Å/cycle, 0.2 Å/cycle, and 0.1 Å/cycle, respectively. Here, Examples 7-1,7-2, and 7-3 were performed in the same manner as in Example 7, exceptfor the feeding amount of the growth inhibitor for forming a thin film.

3) Step Coverage Characteristics

The step coverage of TiN thin films deposited in Example 1 andComparative Example 1 were confirmed by TEM, the results of which areshown in Table 5 below and FIG. 5.

TABLE 5 Example 1 Comparative 1 Step coverage rate (%) 92% 78%

As shown in Table 5, it could be confirmed that the step coverage ofExample 1, in which the growth inhibitor for forming a thin filmaccording to the present disclosure was employed, was significantlyhigher than that of Comparative Example 1, in which the growth inhibitorwas not employed.

In addition, referring to the TEM images shown in FIG. 5, it could beconfirmed that in view of the thickness uniformity of the top andbottom, the step conformality of the TiN thin film deposited in Example1 (SP-TiCl₄) was more excellent as compared to the TiN thin filmdeposited in Comparative Example (TiCl₄).

As set forth above, according to the present disclosure, it is possibleto provide a method for forming a thin film capable of suppressing sidereactions and reducing a deposition rate to appropriately lower a thinfilm growth rate while also removing process byproducts in the thinfilm, thereby preventing corrosion or deterioration and greatlyimproving step coverage and thickness uniformity of the thin film, evenwhen the thin film is formed on a substrate having a complex structure.

What is claimed is:
 1. A method for forming a thin film comprising stepsof: i) adsorbing a growth inhibitor for forming a thin film on a surfaceof a substrate, the growth inhibitor for forming a thin film beingrepresented by Chemical Formula 1 below; and ii) adsorbing a Ti-basedthin film precursor on a surface of a substrate on which the growthinhibitor is adsorbed.AnBmXo  [Chemical Formula 1] wherein A is carbon or silicon, B ishydrogen or a C1-C3 alkyl, X is a halogen, n is an integer of 1 to 15, ois an integer of 1 or more, and m is 0 to 2n+1.
 2. The method forforming a thin film of claim 1, wherein in the step of i) adsorbing thegrowth inhibitor for forming a thin film on the surface of thesubstrate, the feeding time for the growth inhibitor is 1 to 10 seconds.3. The method for forming a thin film of claim 1, wherein the step of i)adsorbing the growth inhibitor for forming a thin film on the surface ofthe substrate comprises a step of injecting the growth inhibitor forforming a thin film into an atomic layer deposition (ALD) chamber andadsorbing the growth inhibitor onto a surface of a loaded substrate. 4.The method for forming a thin film of claim 1, wherein the step of i)adsorbing the growth inhibitor for forming a thin film on the surface ofthe substrate comprises a step of purging the remaining inhibitorunadsorbed on the surface of the substrate for forming the thin filmwith a purge gas.
 5. The method for forming a thin film of claim 1,wherein the step of ii) adsorbing a Ti-based thin film precursor maypreferable comprise a step of purging the remaining unadsorbed Ti-basedthin film precursor with a purge gas.
 6. The method for forming a thinfilm of claim 1, further comprising steps of supplying a reaction gasafter adsorption of a Ti-based thin film precursor on the surface of thesubstrate, and purging reaction byproducts of the Ti-based thin filmprecursor and the reaction gas with a purge gas.
 7. The method forforming a thin film of claim 6, wherein the reaction gas comprises areducing agent, a nitriding agent, or an oxidizing agent
 8. The methodfor forming a thin film of claim 1, wherein the growth inhibitor forforming a thin film and the Ti-based thin film precursor are transferredinto the ALD chamber by a vapor flow control (VFC) method, a deliveryliquid injection (DLI) method, or a liquid delivery system (LDS) method.9. The method for forming a thin film of claim 1, wherein the ratio ofthe feeding amount (mg/cycle) between the growth inhibitor for forming athin film and the Ti-based precursor in the ALD chamber is from 1:1.5 to1:
 20. 10. The method for forming a thin film of claim 1, wherein X ischlorine (Cl).
 11. The method for forming a thin film of claim 1,wherein o is an integer from 1 to
 5. 12. The method for forming a thinfilm of claim 1, wherein the compound represented by Chemical Formula 1is a branched, cyclic or aromatic compound.
 13. The method for forming athin film of claim 1, wherein the compound represented by ChemicalFormula 1 is a liquid at room temperature (22° C.), and has a density of0.8 to 1.5 g/cm³, a vapor pressure (20° C.) of 1 to 300 mmHg, andsolubility in water (25° C.) of 200 mg/L or less.
 14. The method forforming a thin film of claim 1, wherein a reduction rate of a thin filmgrowth rate (Å/cycle) per cycle calculated by the following Equation 1is -5% or less.Reduction rate of thin film growth rate per cycle (%)=[(thin film growthrate per cycle when growth inhibitor for forming thin film is used—thinfilm growth rate per cycle when growth inhibitor for forming thin filmis not used)/thin film growth rate per cycle when growth inhibitor forforming thin film is not used]×100  [Equation 1]
 15. The method forforming a thin film of claim 1, wherein the residual halogen intensity(c/s) of the thin film formed after 200 cycles, which is measured basedon SIMS, is 10,000 or less.
 16. An apparatus for preparing a thin filmcomprising: an atomic layer deposition (ALD) chamber, a first vaporizerfor vaporizing the growth inhibitor for forming a thin film, a firsttransfer unit for transferring the vaporized growth inhibitor into theALD chamber, a second vaporizer for vaporizing a Ti-based thin filmprecursor, and a second transfer unit for transferring the vaporizedTi-based thin film precursor into the ALD chamber.